Alright, so I ended up buying the rest of the SC2 campaigns and am currently powering though them.
Heart of the Swarm was piss easy compared to wings of Liberty, I've never had to dial down the difficulty and there's only one mission I've had to restart a couple of times to adjust my strategy - something I've had to do quite often during WoL and now during LotV. Mission-design-wise, it is fairly varied, although I've been able to use pretty much the exact same strategy in every mission with base building. *insert all-solving-hammer joke* Some units & mutation also feel very gimmicky & situational.
Story-wise it felt just as shaky as WoL did, so I guess it's consistent in that regard. I overall disliked the number of "individual" zerg characters within the Swarm, though I guess with the Overmind & Cerebrates gone, they needed someone for Kerrigan to interact with, and you couldn't just throw her an entourage of infested terrans. Still, it's disappointing but fairly harmless, although I guess WoL set the standard pretty low.
Legacy of the Void has been pretty interesting so far, the Spear of Adun feels a bit more balanced than Kerrigan was, and being able to switch between unit variants before each mission is nice. I do notice that a lot of my strategies devolve into building lots of dragoons & zealots, but hey it got me through the original SC so why not... Difficulty-wise I'd say it's part way between HotS & WoL.
Story-wise however, I do have issues this time, with Blizzard going the corruption route for the N-th ****ing time.
- In Diablo 1 that's alright, they're kind of the forerunner and with all the devilry going on it fits the themes of the games ;
- in SC & Broodwar, infestation is Sci Fi take on the subject, so it's still fresh to a degree and it's mostly focused around Kerrigan & the Zerg ;
Diablo 2 & D2: LoD keep going at it with gusto, it may feel excessive, but that's in line with the first game ;
- in War3 : RoC, well we've got the fallen prince, the chaos orcs, the corrupted night elves & other Aschenvale dwellers, plus as a bonus the demonic demon hunter, that's starting to feel like a bit much ;
- with War3 : FT we can add the Naga as sort-of corrupted night elves, plus more fleshing out of the Scourge-serving nerubians ;
- WoW has had waayyyy too many examples over the years and as far as I know is still milking that type of plotline.
So no, going for yet another corrupting/mind controlling force is not OK. Try to have some properly motivated villains, you used to be able to do that. Your Big Bad should have plenty of arguments to get followers from every factions, so what the hell are you doing ?
Anyway, I think I'm close to the halfway point and I'm having a good time so far.